The present invention relates to an electric power tool provided with a plurality of operation modes.
A conventionally known electric power tool has a motor as a drive source and is configured to be able to be selectively operated at one of a plurality operation modes (hereinafter, referred to as a “multimode electric power tool”).
For example, Japanese Patent No. 3656887 discloses a vibration driver drill configured such that mechanical mechanisms are changed over by rotation of a dial type switching member, thereby to be able to be switched between at least two operation modes of a vibration mode and a drill mode.
Other than the above, for example, an electric power tool is known which is provided with four types of operation modes of a drill mode, a clutch mode, a vibration drill mode and an impact mode, and is configured such that the user can set one of the operation modes by sliding a mode switching lever (see, for example, Japanese Patent No. 4391921).
In the above electric power tool, the drill mode is an operation mode in which rotation of a motor is transmitted as is or with deceleration to an tool output shaft, such as a sleeve, to which a tool bit is attached. The drill mode is used, for example, in fastening of screws and boring.
At the clutch mode, rotation of a motor is also transmitted as is or with deceleration to a tool output shaft. Further, when a rotation torque of the tool output shaft (i.e., rotation torque of a tool element attached to the tool output shaft) reaches or exceeds a predetermined value, a mechanical connection between the motor and the tool output shaft is released so that the rotation of the motor is no longer transmitted to the tool output shaft, thereby to stop rotation of the tool output shaft. The clutch mode is used, for example, in fastening of screws.
At the vibration drill mode, rotation of a motor is also transmitted as is or with deceleration to a tool output shaft. Further, a rotational drive force of the motor can be used to apply intermittent hammering to the tool output shaft in its axial direction. The vibration drill mode is used, for example, in boring relatively hard materials such as cements and tiles.
At the impact mode, rotation of a motor is also transmitted as is or with deceleration to a tool output shaft. Further, a rotational drive force of the motor can be used to apply intermittent hammering to the tool output shaft in its rotation direction. The impact mode can implement operation as a so-called impact driver. The impact mode is used, for example, in fastening of screws and bolts.
As above, a multimode electric power tool that is configured to be able to implement operations at a plurality of operation modes allows various operations with just the one multimode electric power tool. There is no necessity of providing a different electric power tool per operation type. Thus, the multimode electric power tool is very convenient and beneficial for a user of an electric power tool.
However, the conventional multimode electric power tool implements switching of a plurality of operation modes just by switching of mechanical transmission mechanisms. Thus, as the number of types of operation modes is increased, the tool is likely to be increased in size and cost.
Specifically, in the conventional multimode electric power tool, a transmission mechanism for transmitting the rotation drive force of the motor to the tool output shaft is provided per a plurality of operation modes. When the user slides a mode switching lever, the transmission mechanism is also switched in conjunction with the slide manipulation.
On the other hand, the motor which generates the rotation drive force for rotating the tool output shaft is controlled by the same control method regardless of the operation mode. Particularly, it is general that the motor is controlled such that the motor is rotated at a rotation frequency (rotation frequency per unit time; rotation speed) corresponding to a pulled amount of a trigger switch manipulated by the user. When the pulled amount is the maximum, a maximum rotation frequency is achieved.
As noted above, in the conventional multimode electric power tool, the electric control method of the motor is the same regardless of the operation mode, and operation at each operation mode is achieved by switching the mechanical transmission mechanisms in accordance with the operation mode.
Thus, in order to implement an electric power tool provided with more types of operation modes, the types of transmission mechanisms has to be increased. As a whole, configuration of the mechanical mechanisms becomes complex and large. Thus, the conventional configuration in which the operation mode is switched only by switching the mechanical transmission mechanisms has been an obstacle to aiming for improved performance of a multimode electric power tool.
On the other hand, an electric power tool is also known in which control parameters of the motor can be changed by user manipulation. For example, Japanese Utility Model Registration No. 3110344 discloses an electric power tool (electric wrench) in which a user can change a set torque value.
The electric power tool described in Japanese Utility Model Registration No. 3110344 includes two buttons manipulated by a user for changing the set torque value and a display for displaying the set torque value. Thus, the user can manipulate these two buttons to change the set torque value to a desired value.
Such configuration in which the control parameter can be changed by user manipulation can be employed also in the above-described multimode electric power tool. Thereby, functionality and user-friendliness of the multimode electric power tool can be enhanced.
However, if the multimode electric power tool is configured such that the control parameter can be changed per each of the plurality of operation modes, configuration of a manipulation unit such as buttons which the user manipulates for changing the control parameters and a display unit for displaying the control parameters may become complex.
Specifically, for example, if two operation modes are configured such that a set torque value can be changed at one of the operation modes, and a maximum rotation speed of a motor can be changed at the other of the operation modes, the user has to identify the control parameter to be changed. Thus, it is general to provide a manipulation unit and a display unit per operation mode (i.e., per type of control parameter).
However, if the manipulation unit and the display unit are provided per operation mode as such, the manipulation unit and the display unit for changing and displaying the control parameter are increased in number and become complex as the types of operation modes increases at which the control parameter can be changed. A mounting area for mounting these components in the electric power tool is increased, which leads to increase in cost of the electric power tool.